Flowmeters of many different kinds are used to measure fluid flow rates and volumes. Particular flowmeters are selected for ranges of measurements and accuracies. Flowmeters vary from water meters to additive meters and paint meters, which measure, for example, the exact amount of paint which is applied to an automobile body.
Typical flowmeter categories are mass, velocity, displacement and pressure differential meters. Within each category different types of flowmeters exist. Displacement meters include piston, gear, oral gear disc and vane meters.
In positive displacement flowmeters, which have motion, the force of moving meter elements is usually provided by the fluid which flows through the meter. Accuracy and sensitivity to flows over wide ranges are the hallmarks of good flowmeters.
Work continues on improving flowmeters and providing flowmeters of simplified designs which reduce complexity in their component parts, which reduce weight of component parts and which are highly sensitive and quickly start and stop or change speed according to changes in flow volumes.